The invention relates to a device such as an adjuster for a car seat, for enabling a rotary driving member to transmit rotary movement to a driven member in either direction of rotation, while locking the driven member against rotation relative to the drive member.
Devices of this type are known; and one is disclosed in U.S. Pat. No. 5,248,017 wherein an apparatus includes a driving gear for rotating a driven pinion in either of two directions for adjusting the driven pinion, and wherein the pinion is automatically locked in the adjusted positions. Such devices are especially suited as seat adjusters in motor vehicles. A frame-mounted hub is provided for these devices on which the driving wheel and the pinion wheel are mounted. Pairs of clamps are surrounded by a ring attached to the pinion wheel. The inner surface of the pinion wheel includes slanted surfaces for clamping the clamps against the hub. In the locked position, the clamps are pressed against the hub and these slanted surfaces by spring elements and upon rotation of the driving wheel, catches carried by the driving wheel displace the clamps from their locked position to permit the pinion wheel to be rotated by the driving wheel. The clamps lock the pinion wheel in its adjusted positions.
As explained above, the primary application area of this type of device is in the adjustment of the seat back of seats in motor vehicles. Two mutually exclusive types of devices have been used for the adjustment of seat backs. In a first type, a notch style adjuster is operated by means of a release lever or a catch lever, whereby following the release of the catch lever the inclination of a spring-biased seat back is adjusted by applying pressure to the seat back. This construction is used in the United States of America in particular. On the other hand, a continuous adjuster is widely used in Europe, in which case, a continuous seat back adjuster of the type described earlier herein is operated by a driving wheel in the form of a hand wheel to rotate a driven pinion connected to the seat back to achieve an infinite number of adjusted positions.
Both constructions have advantages and disadvantages. The notch style adjuster allows the release of the seat back and quick adjustment into the desired position by means of a hand lever. This is especially beneficial in the case of two-door motor vehicles in which one wishes to reach the back seat, because the seat back can be tilted forward quickly, so that the back seat is more accessible. To that end, it is necessary only to release the lever; whereupon the seat back of the front seat is pushed forward a by a built-in spring. Except for the fact that the adjustment of the seat back is only possible in specific notched positions, the operation is also not without problems, since the seat back must be pushed back into the desired position against the action of the restoring spring after releasing the catch lever. Since constructions of this type are hardly free from play, they tend to rattle or clatter upon movement of the vehicle.
In the construction involving a continuous adjustment it is not possible to quickly tilt the seat back forwardly to access the back seat in two-door vehicles. That required an additional construction that is completely independent of the seat adjustment, which made it possible to push the seat back of the front seat forward. This, however, involves a considerable additional expenditure of money and labor.